As far as I know, only eOffice from
http://www.dynoplex.com can do this...
Out of the box, BlackBerry is
NOT a good
OFFLINE email reader... If you want best email synchronization, you need it to be online on the BlackBerry Network, preferably on a BlackBerry Enterprise Server.
(I use Mailstreet at $23 per month -- and I love its wireless PIM synchronization. Never need to connect cables; any addressbook entries I add, or appointments I add in Microsoft Outlook shows up on my BlackBerry just 5 seconds later. My outlook email folder tree is synchronized too, but not for email messages sent/received BEFORE I enabled the wireless synchronization...)